This proposal involves a study of a new type of salt-soluble chromatin (deoxyribo-nucleoprotein, DNP) formed from insoluble chromatin fibers via an endogenous nucleolytic reaction. The DNP molecules produced appear to be fragments of the original chromatin thread in which the native conformation has been minimally effected. The DNP contains histones and non-histone proteins and a high molecular weight DNA which is maintained in a rather compact configuration. One phase of this research will involve studies on the structure of this DNP. Column chromatography will be used to further purify the DNP and to ascertain the place of chromosomal RNA in the structure. Digestion of the DNP with nucleases will be carried out in an attempt to break up the DNP into its subunits, the so-called nucleosomes. Selective methods for removing histone Hl from the DNP will be used to examine the role this histone has in the structure of chromatin and its subunits. The DNP has a very low template activity when tested with an animal RNA polymerase. Another phase of the proposal concerns experiments to show that the DNP does not have any capacity to bind the enzyme, thus demonstrating that a possible mechanism of gene repression is inherent in the structure of the DNP - the tight packing of the DNP prevents access of the polymerase to the DNA. In order to gain insight on the mechanism of gene activation, experiments will be carried out in an attempt to activate the DNP towards RNA polymerase initiation. Non-histone proteins will be isolated from nuclei and chromatin and fractionated by affinity chromatography using sepharose-linked DNA. The DNP will be treated with he non-histone fractions and activation monitored by addition of RNA polymerase and measurement of initiation.